Die for a semi-product of a combination nipple that connects a flexible hose to a rigid pipe

ABSTRACT

In a die for forging a metal tube to form a semi-product of a unitary combination nipple, a die body has annular first, second and third inner surfaces, and a die cavity. The die cavity includes a large-diameter outer cavity portion with a uniform diameter defined by the first inner surface and adapted to permit insertion of the tube into the die cavity therethrough, a small-diameter inner cavity portion with a uniform diameter smaller than that of the outer cavity portion and defined by the second inner surface, and a polygonal cavity portion disposed between the outer and inner cavity portions and defined by the third inner surface. The second inner surface is located inside the first inner surface, and the third inner surface is located inside the first inner surface but outside the second inner surface.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a die for forging a semi-product of a combination nipple that connects a flexible hose to a rigid pipe, more particularly to a die of the aforesaid type that can reduce processing steps and costs.

[0003] 2. Description of the Related Art

[0004] Referring to FIGS. 1 to 6, in a conventional process of forging a metal circular tube 2 to form a combination nipple 2′ that connects a flexible hose to a rigid pipe, first and second die units 11, 12 are employed. The first die unit 11 is configured to punch a part of the tube 2 so as to form a first semi-product (2A) shown in FIG. 3 that has adjoining large-diameter and small-diameter tubular portions 21, 22. The second die unit 12 is used to punch a junction between the large-diameter and small-diameter tubular portions 21, 22 so as to form a second semi-product (2B) shown in FIG. 5 that has a polygonal portion 23 therebetween. The large-diameter tubular portion 21 is subsequently formed with an external thread in an outer surface thereof so as to serve as a pipe-connecting portion 21′ of the combination nipple 2′, and the small-diameter tubular portion 22 is later formed with a plurality of annular grooves 221 in an outer surface thereof so as to serve as a hose-connecting portion 22′ of the combination nipple 2′, with the polygonal portion 23 serving as a polygonal spanner-engaging portion 23′ of the combination nipple 2′ that is rotatable by a spanner (not shown) . However, as the second semi-product (2B) has to be formed by two separate steps and using two die units 11, 12, the manufacturing costs are relatively high, and the production rate is relatively low.

SUMMARY OF THE INVENTION

[0005] Therefore, the main object of the present invention is to provide a die for a semi-product of a combination nipple that can reduce processing steps and costs, and that can enhance productivity.

[0006] Accordingly, a die of the present invention is adapted for forging a metal circular tube to form a semi-product of a unitary tubular combination nipple. The nipple is employed to connect a flexible hose to a rigid pipe, and has an externally threaded pipe-connecting portion, a hose-connecting portion with a plurality of annular grooves formed in an outer surface thereof, and a polygonal portion that is disposed between the pipe-connecting portion and the hose-connecting portion and that can be rotated by a spanner. The semi-product has a large-diameter circular tubular portion to be formed as the pipe-connecting portion, a small-diameter circular tubular portion to be formed as the hose-connecting portion, and a polygonal portion that is disposed between the large-diameter and small-diameter circular tubular portions. The large-diameter circular tubular portion has an outer diameter larger than that of the small-diameter circular tubular portion and equal to that of the circular tube. The die includes a die body having an annular first inner surface, an annular second inner surface, an annular third inner surface, and a die cavity. The die cavity includes: a large-diameter outer cavity portion with a uniform diameter that is defined by the first inner surface and that is adapted to permit insertion of the circular tube into the die cavity therethrough; a small-diameter inner cavity portion with a uniform diameter that is smaller than that of the outer cavity portion and that is defined by the second inner surface, the second inner surface being located inside the first inner surface; and a polygonal cavity portion disposed between the outer and inner cavity portions and defined by the third inner surface, the third inner surface being located inside the first inner surface and outside the second inner surface.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:

[0008] FIGS. 1 to 6 are perspective views illustrating the steps of forging a metal circular tube into a combination nipple using two die units according to the prior art;

[0009]FIG. 7 is a perspective view of the preferred embodiment of a die according to the present invention;

[0010]FIG. 8 is a perspective view of the preferred embodiment for forging a metal circular tube, with the preferred embodiment shown in section;

[0011]FIG. 9 is a perspective view of the preferred embodiment during forging of the circular tube, the preferred embodiment being shown in section;

[0012]FIG. 10 is a perspective view of a semi-product of a combination nipple, which is formed from the circular tube by means of the preferred embodiment; and

[0013]FIG. 11 is a perspective view of a finished combination nipple that is formed from the semi-product of FIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] Referring to FIGS. 7 and 11, the preferred embodiment of a die 3 according to the present invention is adapted for forging a metal circular tube 4 to form a semi-product 40 of a unitary tubular combination nipple 5. The combination nipple 5 is employed to connect a flexible hose (not shown) to a rigid pipe (not shown), and has an externally threaded pipe-connecting portion 41′, a hose-connecting portion 42′ with a plurality of annular grooves 421 formed in an outer surface thereof, and a polygonal portion 43′ that is disposed between the pipe-connecting portion 41′ and the hose-connecting portion 42′ and that can be rotated by a spanner. In this embodiment, the polygonal portion 43′ is hexagonal. The semi-product 40 has a large-diameter circular tubular portion 41 to be formed as the pipe-connecting portion 41′, a small-diameter circular tubular portion 42 to be formed as the hose-connecting portion 42′, and a polygonal portion 43 that is disposed between the large-diameter and small-diameter circular tubular portions 41, 42. The large-diameter circular tubular portion 41 has an outer diameter larger than that of the small-diameter circular tubular portion 42 and equal to that of the circular tube 4.

[0015] As shown in FIG. 7, the die 3 according to the present invention includes a hollow tubular die body 30 with top and bottom ends, and having an annular first inner surface 301, an annular second inner surface 302, an annular third inner surface 303 interposed between the first and second inner surfaces 301, 302, and a die cavity. The die cavity includes a large-diameter outer cavity portion 32, a small-diameter inner cavity portion 33, and a polygonal cavity portion 34. The outer cavity portion 32 has a uniform diameter that is defined by the first inner surface 301 and that is equal to the outer diameter of the circular tube 4 so as to be adapted to permit insertion of the circular tube 4 into the die cavity therethrough. The inner cavity portion 33 has a uniform diameter that is smaller than that of the outer cavity portion 32 and that is defined by the second inner surface 302. The second inner surface 302 is located inside the first inner surface 301. The polygonal cavity portion 34, which is hexagonal in this embodiment, is disposed between the outer and inner cavity portions 32, 33 and is defined by the third inner surface 303. The third inner surface 303 is located inside the first inner surface 301 and outside the second inner surface 302. In addition, the top end of the die body 30 is formed with a plurality of angularly equidistant threaded holes 31 adapted for threaded engagement with a die driving device (not shown) of a forging machine.

[0016] Referring to FIGS. 8 to 10, when the die 3 is driven vertically downward to punch the circular tube 4, since the outer cavity portion 32 has a diameter equal to the outer diameter of the circular tube 4, the part of the circular tube 4 that corresponds to the outer cavity portion 32 remains intact, whereas the second inner surface 302, which defines the inner cavity portion 33 having a diameter smaller than that of the circular tube 4, applies pressure radially and inwardly, thereby forming the semi-product 40 with the large-diameter and small-diameter circular tubular portions 41, 42, which correspond respectively to the outer and inner cavity portions 32, 33. In addition, a polygonal portion 43 is simultaneously formed between the large-diameter and small-diameter circular tubular portions 41, 42 at the part corresponding to the polygonal cavity portion 34.

[0017] Subsequently, the large-diameter circular tubular portion 41 is tapped to form the externally threaded pipe-connecting portion 41′, and the small-diameter circular tubular portion 42 is formed with the grooves 421, thereby completing the combination nipple 5.

[0018] It can be appreciated from the aforesaid that, the die body 30 is provided with the polygonal cavity portion 34 that is disposed between the outer and inner cavity portions 32, 33, so that the circular tube 4 can be formed with the large-diameter and small-diameter circular tubular portions 41, 42 and the polygonal portion 43 in one operation and by employing a single die 3. Compared to the prior art that requires two die units and two processing steps, as described hereinabove, the present invention can simplify the manufacturing process and reduce manufacturing costs, as well as increasing productivity.

[0019] While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. 

I claim:
 1. A die for forging a metal circular tube to form a semi-product of a unitary tubular combination nipple, the nipple being employed to connect a flexible hose to a rigid pipe, and having an externally threaded pipe-connecting portion, a hose-connecting portion with a plurality of annular grooves formed in an outer surface thereof, and a polygonal portion that is disposed between the pipe-connecting portion and the hose-connecting portion and that can be rotated by a spanner, the semi-product having a large-diameter circular tubular portion to be formed as the pipe-connecting portion, a small-diameter circular tubular portion to be formed as the hose-connecting portion, and a polygonal portion that is disposed between the large-diameter and small-diameter circular tubular portions, the large-diameter circular tubular portion having an outer diameter larger than that of the small-diameter circular tubular portion and equal to that of the circular tube, said die comprising: a die body having an annular first inner surface, an annular second inner surface, an annular third inner surface, and a die cavity which includes a large-diameter outer cavity portion with a uniform diameter that is defined by said first inner surface and that is adapted to permit insertion of the circular tube into said die cavity therethrough; a small-diameter inner cavity portion with a uniform diameter that is smaller than that of said outer cavity portion and that is defined by said second inner surface, said second inner surface being located inside said first inner surface; and a polygonal cavity portion disposed between said outer and inner cavity portions and defined by said third inner surface, said third inner surface being located inside said first inner surface and outside said second inner surface. 